1. Field of the Invention
The present invention relates to a method for manufacturing an image forming apparatus having a spacer arranged in a container to keep a gap between image forming means and the interior of the container.
2. Related Background Art
Conventionally, as an image forming apparatus using a cold cathode electron source, there has been known an apparatus the section of which is shown in FIGS. 2A to 2C, (such as disclosed in the specification of Japanese Patent Laid-Open Application No. 02-299136).
This image forming apparatus uses the cold cathode electron source which is called the surface conductive type electron discharging device. Each of the electron discharging devices 205 is produced with the electrodes 202 and 203, and electron discharging unit 204 formed across the electrodes 202 and 203, which are arranged on a substrate 201. Also, for the face plate 206 which is arranged to face the substrate 201, the fluorescent surface 208 and metal back 211 are formed on the inner face of the glass plate 207. For the color image forming apparatus, the fluorescent surface 208 usually comprises the black conductive material 209 which is called black stripes as shown in FIG. 3, and the metal back 211 which covers both the black stripes 209 and the fluorescent device 210 after patterning the fluorescent device 210 on the glass plate 207. The provision of the black stripes 209 is aimed at making the mixture of colors or the like less conspicuous by arranging the separating part between each of the coatings of fluorescent devices 210, which are in three primary colors needed for the color fluorescent surface, and at the same time, it is aimed at preventing the contrast from being lowered due to the reflection of external light on the fluorescent surface 208.
The purpose of the provision of the metal back 211 is to prevent the potential from being lowered due to the accumulation of charges (electron) on the fluorescent device 210 having the resistance ratio of as high as 10.sup.10 to 10.sup.12 .OMEGA..multidot.cm in general, and to enable it to function as electrodes to apply voltage for use of the electron beam acceleration, and also, to enhance the luminance by the mirror surface reflection of the light of those emitted from the fluorescent device 208 to the inner surface side of the apparatus. The purpose of the provision of the metal back is also to protect the fluorescent device 210 from negative ionic collision, among some others. As the material which is suitable for the purposes described above, Al is usually used. The metal back 211 is formed by the Al vacuum apparatus after the formation of the back stripes 209 and the fluorescent device 210 by means of patterning subsequent to the process called filming (that is, to coat an organic film on the black stripes 209 and the fluorescent device 210). After that, the organic film is removed by burning to complete the metal back. However, the strength of the metal back 211 of the fluorescent surface 208 is weak to the extent that it is peeled off when rubbed by a finger particularly after the metal back process is performed.
Also, a plurality of spacers 212 are arranged as the supporting members to resist the atmospheric pressure in order to keep the substrate 201, on which the electron discharging devices 205 are formed, and the face plate 206 substantially in a constant gap.
Among the image forming apparatuses having the aforesaid spacers in the interior of the container thereof, there are some in which many numbers of spacers are used to resist the atmospheric pressure between the face plate and the rear plate by use of the bonding material such as frit glass. In this case, it is often practiced that the face plate is arranged on the rear plate wiring in high precision, and then, it is bonded with the face plate for arrangement. Here, the bonding material made by frit glass is coated on the rear plate wiring, and the spacers to resist the atmospheric pressure are installed in high precision. Then, the process should go through the positioning to be effectuated, while the substrate is being heated uniformly as a whole. However, there a problem is encountered that this process is complicated or it may take a long time to complete it.